a) Field of the Invention
The present invention relates to a miniature motor unit which has a configuration wherein a miniature motor is integrated with a motor mounting member.
b) Description of the Prior Art
Permanent-magnet field type miniature DC motors have conventionally been widely used for various types of compact appliance, portable appliances in particular, since these motors can be driven with batteries and have large torques for compact sizes of the motors. To mount these miniature motors on appliances to be driven with the motors, it is general to attach the motors to motor mounting members with screws.
FIGS. 1A and 1B show an outside casing of a conventional miniature motor; FIG. 1A being a front view of a bottom of the casing and FIG. 1B being a side sectional view of the casing. FIG. 2 is a partially sectional side view showing a condition where the motor using the outside casing is attached to a motor mounting member.
In FIGS. 1A and 1B, a reference numeral 1 represents the outside casing of the motor composed of an iron plate which is formed by drawing work or the like into a cup consisting of a cylindrical portion 1a and a bottom surface portion 1b. Outside a center of the bottom surface portion 1b, a bearing accommodator 2 is formed by drawing work to accommodate a bearing for an output shaft of a rotor. A reference numeral 3 designates a center hole to accommodate the bearing. Reference numeral 4a and 4b denote holes which are tapped inside and embossed inward at locations of the bottom surface portion which are apart 180.degree. and symmetrical with regard to the center.
In FIG. 2, a reference symbol M represents a motor which uses the outside casing 1, a reference numeral 5 designates a cover casing which is fitted over the outside casing 1 and made of an insulating material, a reference numeral 6 denotes a terminal for connection to a power source and a reference numeral 7 represents a rotor shaft. A reference numeral 8 designates a motor mounting member of an appliance (compact pump or the like) which is to be driven with the motor; the motor mounting member consisting, like the outside casing, of a cylindrical portion and a bottom surface portion, and having holes formed in the bottom surface portion at locations corresponding to the tapped holes 4a and 4b formed in the outside casing 1. In addition, a center hole is formed in the bottom surface portion of the motor mounting member 8 to insert the bearing accommodator 2.
The motor M is attached to the motor mounting member 8 by bringing the motor M into contact with the motor mounting member 8 so that the bottom surface portion of the outside casing is brought into contact with the bottom surface portion of the motor mounting member 8, and tightening screws 9a and 9b into the tapped holes 4a and 4b of the outside casing 1.
However, the conventional miniature motors such as that described above require screw tightening in narrow spaces of the motor mounting member and have a large number of defects including a defect that the motors hardly allow assembling works to be automated.